Sx-990 was working 1 month ago, now no sound

[davidosis]

Okay, this my first endeavor in investigating vintage receivers. I have my dads 1970 pioneer sx-990. It was outputting audio as recently as a month ago (left/right etc). Recently powered it on to discover no Audio output. Fm, am, phono, and headphone Jack are all quiet with no sound whatsoever.

the only sound I get is when I power it on I get the pop from the power selector knob thru the speakers. The large 2 amp fuses, and the line voltage fuse are good.

where does a rookie begin an investigation besides a repair shop. (May end up at a shop but I’m interested in this)

Thx!

dave b
Seattle

 

[TomSc]

Both channels out usually points to a power supply or protection issue. I don't see a protect circuit on this one. Now just to be thorough, double check your connections - and the tape monitor switch. This receiver also has Pre Out/Pwr In connections on the back. Make sure the jumpers are still there.

Beyond that, how comfortable are you with a multimeter?

 

[davidosis]

Both channels out usually points to a power supply or protection issue. I don't see a protect circuit on this one. Now just to be thorough, double check your connections - and the tape monitor switch. This receiver also has Pre Out/Pwr In connections on the back. Make sure the jumpers are still there.

Beyond that, how comfortable are you with a multimeter?

I’m comfortable with a multimeter. HOWEVER the preamp out has no jumper on it. It may have been bumped and fallen off? Not sure. Does the preamp need to be jumpered out???

well turns out my son was trying to connect his music and removed them.

jeez - hours of my life…well at least everything got deoxit now and new lamps.

thx for this. Priceless

 

[larryderouin]

Kids..........Get ya Every time. Wait till you have grandkids and they want to play with the gear. I have a R2R tape of 1812 Overture, using Cannons from West Point, etc. and had it down fairly low. (SX-939 pushing NLA's). Grandson, who was 3 at the time had listened to it a few times before and loved when the cannons go off. I was coming back from a head call when he put the Volume to what he calls "The Neighbors 2 blocks down need to hear this" or what I term "ALL HELL BREAKS LOOSE!". It was literally a replay of the opening shot of Back to the Future in Doc Browns house. As soon as the cannons fired, one cone blew out, and the 939 went into protection from the speaker short.

He got lectured, I got to change my shorts and speakers (rebuilt the blown driver and had the other channel spkr sweep tested). He's 10 now with his own system (Fisher 160-T, Dual 1009, KLH 17's., and doesn''t touch mine anymore except when I'm in pushover mode. .

 

[TomSc]

Glad it was an easy fix!

Kids....I guess I've been lucky. No disasters with the audio gear when they were younger. No grandkids...yet. Maybe I'll put a lock on the door to the man-cave when the time comes!